Video from a National Geographic expedition to Antarctica shows killer whales working together to "wave wash" a crabeater seal off sea ice and into the water. Is that a sign of whale culture?

The teamwork is undeniable: Four orcas race through the Southern Ocean toward a seal stranded on sea ice. At the last minute, they dive simultaneously, creating a wave that swamps the floe, washing the crabeater seal—a potential meal—into the drink.

The seal gets away. But maybe not for the reason you think.

Stunning video footage shot in early January by the Lindblad team on a National Geographic Lindblad Expedition in Grandidier Channel, on the western side of the Antarctic Peninsula, captures the extent to which the White Continent's killer whales—technically dolphins—work as a unit when hunting food.

The whales repeatedly speed together, building a swell large enough to rock the tiny platform of ice and dunk the seal. When the seal quickly shuffles back onto the safety of its slab, the whales nudge the ice from below, breaking it into smaller bits. On other occasions, teams of orcas have been known to flip ice floes over. When ice floes are too large, whales will dive in a way that creates waves beneath the ice, hoping to shatter slabs from below.

"I've seen this type of behavior many times," says Ari Friedlaender, an Antarctic whale expert and National Geographic explorer, reached by phone in Punta Arenas, where he was boarding a plane for Antarctica for another season of whale research. "They coordinate, there are vocalizations, they work in concert. It's an amazing cooperative behavior to behold."

Says Robert Pitman, an orca expert with the National Oceanic and Atmospheric Administration, who was written research papers on this behavior, "It's possible that a single animal could knock a seal off, too. But it works so much better in a group."

This teamwork is a sign of learning and intelligence—and of a behavior entirely different from other orcas, including many living nearby. Some might call it a type of culture.

Exploring Whale Culture

Brian Skerry, a National Geographic photographer, has spent years studying and photographing the activities of whales and dolphins, and is currently at work on a multiyear project to try and explore and document whale culture.

There is no clear, accepted definition of culture, but scientists generally agree that culture includes a community's ability to create and share behaviors and pass them along from one generation to the next. Anthropologists and zoologists have long been divided over whether non-human species truly experience culture, but cetaceans—along with primates—include many species, such as killer whales, that keep the debate lively.

"Orcas are the largest and arguably the most intelligent species of dolphin," Skerry says. And dolphins are among the most sophisticated animals when it comes to developing unique feeding strategies depending on their geography.

For a 2015 National Geographic cover story about dolphin intelligence, for example, Skerry photographed many species feeding. In the Bahamas, off the coast of Bimini, bottlenose dolphins would use echolocation to find fish hidden in the sand along the sea floor, then turn completely vertical and use their beaks—called rostrums—to dig their meal out. Meanwhile, not far away in Florida Bay, the same species hunted an entirely different way. They stirred up the mud in clouds to surround mullet fish. When the fish fled the muddy circles, other dolphins were there to eat them.

"It's generational learning," Skerry says. These behaviors are learned and taught because they are strategies that work in a given location.

Killer whales do things similarly. In Patagonia, related species of orcas nose right onto the shore, picking seal pups right off the beach, a behavior they picked up from family members.

"You find this a lot with these matrilineal societies," Skerry says. He has a picture from Argentina of a mother orca flipping a fur seal pup out of the water. In one corner of the frame, an orca calf can be seen. "That's what happens in Antarctica. These scary smart animals are teaching each other."

The Uniqueness of Wave-Washers

In Antarctica, some orcas rely mostly on fish and penguins. Others largely hunt minke whales. Then there are the wave-washing orcas. All three types are genetically distinct. They don't interbreed. They may even be distinct species.

It's not entirely clear why their feeding strategies are so different. But none is more intense than the feeding of the wave-washers.

That behavior was first formally identified in 1981 when seven whales were witnessed swimming directly at an ice floe and swamping a seal. But it wasn't reported again until 2008. Then, in 2009, Pitman and his colleagues witnessed the behavior 22 times in 12 days, suggesting it was widespread.

When the orcas hunted they started by poking their nose to the sky and "spy hopping" to try and identify which species of seal is on the ice. Once the seal hits the water, the orcas drown it rather than biting it, presumably to make eating the parts they fancy easier.

The orcas travel in family groups, and the hunters are each related. That makes cooperative fishing easier—"When you hunt with a group you’re related to, communication is just easier," Pitman says. "And they will do it together for decades."

Pitman has watched them take three seals in just a few hours. Over a lifetime, the females in the group may be party to the killing of 10,000 seals, he says.

“Sophisticated Societies”

Skerry says the goal of his work is to help people see life in the ocean differently—that there are far more complex interactions taking place than we might first think.

"It's not a place filled with mindless cold-blooded creatures," he says. "There are complex and sophisticated societies in the sea, civilizations, with their own dialects and languages and parenting and feeding strategies. And we only see a fraction of this."

And, Skerry adds, we understand even less.

As if to prove his point, Pitman says wave-washing orcas in Antarctica almost exclusively eat Weddell seals—not crabeater seals. They are pretty good when spy-hopping at distinguishing one species from another.

But they aren't perfect.

"They are fairly picky about what they want, and sometimes they would wash a seal off, realize it was the wrong species, and then let it go," Pitman says.

That he says, may actually be what happened in this video. Orcas, trained well to see underwater, most likely tried to wash the seal into the drink—only to eventually figure out it wasn't the meal they were looking for.

"It'd be pretty hard for a seal in this situation to actually get away," Pitman says. "My guess is they swam off and left it. They may have actually let it get away."